// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/base_paths.h"
#include "base/command_line.h"
#include "base/files/file_path.h"
#include "base/logging.h"
#include "base/mac/foundation_util.h"
#include "base/native_library.h"
#include "base/path_service.h"
#include "base/threading/thread_restrictions.h"
#include "ui/gl/gl_bindings.h"
#include "ui/gl/gl_context_stub_with_extensions.h"
#include "ui/gl/gl_gl_api_implementation.h"
#include "ui/gl/gl_implementation.h"
#include "ui/gl/gl_osmesa_api_implementation.h"

namespace gfx {
namespace {
    const char kOpenGLFrameworkPath[] = "/System/Library/Frameworks/OpenGL.framework/Versions/Current/OpenGL";
} // namespace

void GetAllowedGLImplementations(std::vector<GLImplementation>* impls)
{
    if (base::CommandLine::ForCurrentProcess()->HasSwitch(
            switches::kEnableUnsafeES3APIs)) {
        impls->push_back(kGLImplementationDesktopGLCoreProfile);
    }
    impls->push_back(kGLImplementationDesktopGL);
    impls->push_back(kGLImplementationAppleGL);
    impls->push_back(kGLImplementationOSMesaGL);
}

bool InitializeStaticGLBindings(GLImplementation implementation)
{
    // Prevent reinitialization with a different implementation. Once the gpu
    // unit tests have initialized with kGLImplementationMock, we don't want to
    // later switch to another GL implementation.
    DCHECK_EQ(kGLImplementationNone, GetGLImplementation());

    // Allow the main thread or another to initialize these bindings
    // after instituting restrictions on I/O. Going forward they will
    // likely be used in the browser process on most platforms. The
    // one-time initialization cost is small, between 2 and 5 ms.
    base::ThreadRestrictions::ScopedAllowIO allow_io;

    switch (implementation) {
    case kGLImplementationOSMesaGL: {
        // osmesa.so is located in the build directory. This code path is only
        // valid in a developer build environment.
        base::FilePath exe_path;
        if (!PathService::Get(base::FILE_EXE, &exe_path)) {
            LOG(ERROR) << "PathService::Get failed.";
            return false;
        }
        base::FilePath bundle_path = base::mac::GetAppBundlePath(exe_path);
        // Some unit test targets depend on osmesa but aren't built as app
        // bundles. In that case, the .so is next to the executable.
        if (bundle_path.empty())
            bundle_path = exe_path;
        base::FilePath build_dir_path = bundle_path.DirName();
        base::FilePath osmesa_path = build_dir_path.Append("osmesa.so");

        // When using OSMesa, just use OSMesaGetProcAddress to find entry points.
        base::NativeLibrary library = base::LoadNativeLibrary(osmesa_path, NULL);
        if (!library) {
            LOG(ERROR) << "osmesa.so not found at " << osmesa_path.value();
            return false;
        }

        GLGetProcAddressProc get_proc_address = reinterpret_cast<GLGetProcAddressProc>(
            base::GetFunctionPointerFromNativeLibrary(
                library, "OSMesaGetProcAddress"));
        if (!get_proc_address) {
            LOG(ERROR) << "OSMesaGetProcAddress not found.";
            base::UnloadNativeLibrary(library);
            return false;
        }

        SetGLGetProcAddressProc(get_proc_address);
        AddGLNativeLibrary(library);
        SetGLImplementation(kGLImplementationOSMesaGL);

        InitializeStaticGLBindingsGL();
        InitializeStaticGLBindingsOSMESA();
        break;
    }
    case kGLImplementationDesktopGL:
    case kGLImplementationDesktopGLCoreProfile:
    case kGLImplementationAppleGL: {
        base::NativeLibrary library = base::LoadNativeLibrary(
            base::FilePath(kOpenGLFrameworkPath), NULL);
        if (!library) {
            LOG(ERROR) << "OpenGL framework not found";
            return false;
        }

        AddGLNativeLibrary(library);
        SetGLImplementation(implementation);

        InitializeStaticGLBindingsGL();
        break;
    }
    case kGLImplementationMockGL: {
        SetGLImplementation(kGLImplementationMockGL);
        InitializeStaticGLBindingsGL();
        break;
    }
    default:
        return false;
    }

    return true;
}

bool InitializeDynamicGLBindings(GLImplementation implementation,
    GLContext* context)
{
    switch (implementation) {
    case kGLImplementationOSMesaGL:
    case kGLImplementationDesktopGL:
    case kGLImplementationDesktopGLCoreProfile:
    case kGLImplementationAppleGL:
        InitializeDynamicGLBindingsGL(context);
        break;
    case kGLImplementationMockGL:
        if (!context) {
            scoped_refptr<GLContextStubWithExtensions> mock_context(
                new GLContextStubWithExtensions());
            mock_context->SetGLVersionString("3.0");
            InitializeDynamicGLBindingsGL(mock_context.get());
        } else
            InitializeDynamicGLBindingsGL(context);
        break;
    default:
        return false;
    }

    return true;
}

void InitializeDebugGLBindings()
{
    InitializeDebugGLBindingsGL();
    InitializeDebugGLBindingsOSMESA();
}

void ClearGLBindings()
{
    ClearGLBindingsGL();
    ClearGLBindingsOSMESA();
    SetGLImplementation(kGLImplementationNone);

    UnloadGLNativeLibraries();
}

bool GetGLWindowSystemBindingInfo(GLWindowSystemBindingInfo* info)
{
    return false;
}

} // namespace gfx
